In the past, video cameras or other sources of video imagery produced analog signals that were passed on to monitors, editing stations, post production, etc. via coaxial cables. With the advent of digital video cameras, and other devices transmitting a high quality digital video signal, coaxial cables are often unsatisfactory. Significant signal degradation occurs when the distance between the source and the user of the signal is over 100 meters. Fiber optic systems have been used to transmit a variety of analog and digital signals. Typically, these signals involve a number of technologies, including broadcast quality video cameras, broadcast remote digital video broadcasting systems including drop distribution, post production point-to-point links, studio matrix digital video switching networks, serial digital interface video transport for high definition television, high quality radiology and other medical systems, sports, special events, studio broadcast programming, etc.
Prior digital image transmitting systems have been quite limited and specialized. For example, Lang in U.S. Pat. No. 5,164,839 describes a system for storing compressed digital video source information on magnetic media, then transmitting it to a remote VCR over a fiber optic cable. This system is limited in video rate transmission and degrades signal quality through compression.
Transmitting telephone signals via fiber optics is described by Schussler in U.S. Pat. No. 4,441,180. A multiplexing system for simultaneously transmitting a number of signals over a fiber optic system is described by Bell in U.S. Pat. No. 4,061,577. Kostreski, in U.S. Pat. No. 5,534,912, describes a “video on demand” system which transmits video signals over fiber optics.
Prior systems such as these do not provide the ideal combination of functions that will provide transmission over longer distances without signal degradation and avoiding compression, will comply with requirements of serial digital interface (SDI), digital video broadcasting (DVB) and high definition television (HDTV) systems and provide flexibility in furnishing a variety of data rates with automatic lock-on.
Thus, there is a continuing need for improved fiber optic cable transmitters and receivers for use with uncompressed digital signals from broadcast cameras and the like, which permits transmission up to about 350 meters with automatic cable equalization and a communications link up to about 40 kilometers without significant signal degradation, utilize an uncompressed digital signal for optimum quality, will automatically lock on any of a plurality of data rates, and provide status indicators for power regulation, signal strength, data rate and serial digital interface lock/unlock.